Cement compositions and the preparation thereof

ABSTRACT

THE WATER CONTENT OF HYDRAULIC CEMENT MIXES FOR A GIVEN PLASTICITY IS REDUCED, AND THE STRENGTH OF THE HARDENED CONCRETE PRODUCED THEREFROM IS INCREASED BY THE INCORPORATION OF INOSITOL IN SAID MIXES. EARLY STRENGTH IS INCREASED, AND THE RETARDATION OF THE RATE OF SET IS LESS THAN THAT NORMALLY ENCOUNTERED IN OBTAINING THE DESIRED ADVANTAGES IN THE PROPERTIES OF THE MIXES. THE INOSITOL IS EMPLOYED IN AN AMOUNT WITHIN THE RANGE OF FROM ABOUT 0.005% TO ABOUT 0.75% BY WEIGHT, PREFERABLY FROM ABOUT 0.10% TO ABOUT 0.25% BY WEIGHT OF CEMENT. SET ACCELERATORS CAN ALSO BE INCORPORATED IN THE CEMENT MIX, THE PROPERTIES OF THE ACCELERATORS AND SAID INOSITOL BEING ADDITIVE SO THAT AN INCREASE IN THE COMPRESSIVE STRENGTH OF THE HARDENED MIX IS ACHIEVED WHILE, AT THE SAME TIME, INCREASING THE RATE OF SET OF THE MIX INCLUDING SAID INOSITOL AND ACCELERATORS.

Int. Cl. C04b 7/02 US. Cl. 106-90 36 ClalmS ABSTRACT OF THE DISCLOSURE The water content of hydraulic cement mixes for a given plasticity is reduced, and the strength of the hardened concrete produced therefrom is increased by the incorporation of inositol in said mixes. Early strength is increased, and the rfiar'dation of the rate of set is less than that normally encountered in obtaining the desired advantages in the properties of the mixes. The inositol is employed in an amount within the range of from about 0.005% to about 0.75% by weight, preferably from about 0.10% to about 0.25% by weight of cement. Set accelerators can also be incorporated in the cement mix, the properties of the accelerators and said inositol being additive so that an increase in the compressive strength of the hardened mix is achieved while, at the same time, increasing the rate of set of the mix including said inositol and accelerators.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to hydraulic cement mixes. More particularly, it relates to such mixes in which improved properties are obtained upon hardening Without adverse efiect upon the set characteristics of the mixes.

Description of the prior art It is a basic rule of cement technology that greater compressive strengths are obtained when reduced quantities of water are utilized in hydraulic cement mixes. Many admixtures employed to achieve such water reduction and improved compressive strength are known to act also as set retarders. As retarders, such admixtures slow the chemical process of hydration so that the concrete remains plastic and workable for a longer time than concrete without such a retarder. Among the materials commonly used for water reduction and improved compres sive strength, which also act as set retarders, are the lignosulfonates, such as calcium lignosulfonate; salts of hydroxycarboxylic acids; sugars such as glucose (dextrose), maltose and the like; and highly polymerized polysaccharides, such as dextrins.

Admixtures having set retarding properties are sometimes employed primarily because of such properties, with improved compressive strength being a supplemental benefit. Retarders are used, for example, to delay the set of cement during difiicult placements that require the concrete to be in a plastic condition for a longer than normal period of time. Retarders are also used to overcome undesired acceleration of set during hot weather.

In other circumstances, admixtures are added to achieve water reduction and greater strength although these benefits are accompanied by an undesired retardation of the rate of development of set and sometimes of early strength of the concrete. To overcome these undesirable effects, well known accelerators that increase the rate of hydration for early strength development are frequently used to overcome the retarding tendency of the water reducer. Calcium chloride and triethanolamine are commonly employed for this purpose. There is, nevertheless, a need in 3,725,097 Patented Apr. 3, 1973 ice the industry for admixtures having the desired eifect on compressive strength and water content, while reducing the retarding tendencies normally associated with such admixtures. In U.S. Pat. 3,432,317, saccharide polymers composed of glucose units having a size range of from three to one the order of twenty-five glucose units are disclosed as being more advantageous than more highly polymerized polysaccharides and more highly depolymerized products. As these exists a wide range of admixtures for achieving specific modifications in the properties of cement mixes and hardened concrete products, there also exists a need for additional admixtures that enhance desired properties of hardened concrete while producing less of the corresponding undesired eflects than was accomplished with many of the conventional admixtures, such as those referred to hereinabove.

It is an object of the present invention, therefore, to provide an improved hydraulic cement mix.

It is another object of the invention to provide a process for increasing the strength of concrete without undue retardation of the rate of set and early strength.

It is another object of the invention to provide a hydraulic cement mix having enhanced compresive strength and reduced water requirements for a given plasticity together with an acceptable rate of set.

It is a further object of the invention to provide a process for producing a hydraulic cement mix having improved compressive strength and an acceleration in the rate of set.

It is a further object of the invention to provide a hydraulic cement mix having improved compressive strength and an acceleration in the rate of set.

With these and other objects in mind, the invention is hereinafter set forth in detail, the novel features thereof The objects of the invention are achieved by the incorporation of inositol into hydraulic cement mixes in an amount sufi'icient to increase the compressive strength of the hardened concrete upon setting of said mixes. Compressive strength of said mixes, including early strength, is increased thereby, the water requirements of the mix are lowered, and the retardation of the rate of set is less than that normally accompanying such improvement in the compressive strength of the hardened mix. The improvement in the compressive strength of the hardened concrete obtained by the incorporation of inositol in the hydraulic cement mix is enhanced by the greater dosages of inositol that can be employed, with accompanying increase in strength, compared with other known admixtures without excessive retardation of set. Where excessive retardation of set is tolerable in particular circumstances, the use of still larger dosages of inositol result in further improvements in the compressive strength of the hardened concrete. By the use of small amounts of conventional accelerators in addition to inositol, the desired improvements in compressive strength are obtained while accelerating the rate of hydration and set.

DETAILED DESCRIPTION OF THE INVENTION Inositol, C H (OH) -2H O, is also known as hydroxycement concretes and mortars, and dry mixes for making such concretes and mortars, in amounts sufficient to increase the compressive strength of the hardened mix upon setting thereof. For this purpose, inositol will generally be incorporated into said cement mixes in an amount dextrose produced a 7-day compressive strength of 3375 p.s.i. and a 28-day strength of 5250 p.s.i. Retardation of the rate of set was 2 /2 hours at this dosage level, as compared with the /2 hour retardation produced by inositol in corresponding mix No. 5. As the dosage of dextrose is 5 within the range of from about 0.005% to about 0.75% increased beyond th1s level, excessive retardation of set is by weight of cement. Within this range, appreciable imobserved. The results shown for Cement No. 2, i.e. mix provement in strength is obtained when inositol is in- Nos. 6-10, on the other hand, clearly indicate that inositol corporated in an amount ranging from about 0.025% to can be added in dosages of up to 0.25% with less retardaabout 0.25 with retardation of the rate of hardening 10 tion of set than produced by dextrose at about 0.100%. being minimized at inositol additions within the range of As also shown by the results for said Cement No. 2, such from about 0.025% to about 0.10% by weight of cement. larger inositol dosages result in a greater improvement in At dosages above 0.25 particularly in the range of from 28-day compressive strength than is obtained with acceptabout 0.50% to about 0.75% by weight of cement, inable levels of dextrose. Such significant improvements are creasing amounts of inositol continue to result in further obtained with inositol at dosages of up to about 0.25 improvement in compressive strength although the retarexcessive retardation being observed as larger dosages of dation of the rate of set also increases at such higher inositol are employed. In those applications in which i o ito1 do a es, excessive retardation as defined by ASTM standards can For purposes of illustrating the advantageous results be tolerated or is desired, further highly significant imobtainable by the practice of the present invention, plain provements 1n 28-day compressive strength can be concrete mixes were prepared and compared with such achieved, particularly as evidenced by the results for mixes in which inositol has been incorporated in varying Ce mlX at the additive l e The imdosages. The same type and brand of cement was used provemen In terms of reducing water requirements in each mix, and the proportion and kind of coarse and achieved by use of inositol is particularly apparent at the fine aggregate employed were substantially the same. A hlgher dosage levels of inositol. fii i m nt f water was dd d t ach i t ff ct It is within the scope of the invention to incorporate in hydraulic setting of the cement and to produce concrete the Cement mixes prepared as herein provided other addimixes of essentially the same consistency, as measured by tives known in the art for the express purpose for which the slump cone. they are normally employed. Such other additives may, The results were as shown below in Table No. I: for example, be air-entraim'ng agents, air-detraining TABLE I Compressive Percent strength of addition Water, gal.l Air,vol. concrete,p.s.i.in Rateoihardening additive by cu. yd. of percent oi'---- relativetoplainmix, Mix No: Additive wt.eernent concrete concrete 7 days 28days hrs.

Cement No.1:

1 None 35.7- 1.5 2.870 4,630 0. 2 Inositol 0.025 35.4 1.5 2,880 4,810 0. a 35.2 1.5 3,000 5,025

37.1 1.0 2,735 4,405 0. 35.5 1.8 3,035 5,070 +1. 34.8 2.0 3.105 5,400 +114. 34.6 1.9 3,085 6,500 Ex. re. setting. 1 33.8 1.9 2,960 5,890 Excessive retardation.

l Retardation 01 set is indicated by a sign.

By way of comparison, mixes of the type employed in Cement No. 1 were prepared in which dextrose was employed as an admixture in place of the inositol incorporated in mix Nos. 2-5. While dextrose produced somewhat larger improvements in compressive strength than accomplished by inositol at relatively smaller dosages, such increase in strength was accompanied by a more rapid rate of retardation of the rate of set, reaching excessive retardation at a much lower dosage level than that at which inositol causes excessive retardation. Thus, at an 0.025% dosage, dextrose produced a 7-day strength of 3110 p.s.i. and a 28-day strength of 4840 p.s.i. without noticeable eflect on the rate of set. At a dosage level of 0.100%,

agents, pozzoulanic materials, fly-ash, coloring agents, water repellents, set accelerators, and the like. Inositol may also be employed in conjunction with a combination of such cement additives to produce desired changes in the physical properties of the concrete being produced. In this regard, it should be noted that inositol is significantly additive in its efiect on concrete when employed with other agents known in the art. This additive eifect is illustrated by the results set forth in Table No. II relating to the use of inositol in combination with known set accelerators, the preparation of the cement mixes and the method of testing being the same as described above with reference to Table No. I.

TAB LE 11 P R r s ren 0 Percent addition oi additive 1 Water, conarete, hard ifirfg gaL/cu. Air, vol. p.s.i. in relative to Triethyd. of percent of plain Mix No. Inositol CaCh anolamine concrete concrete 7 days 28 days mix, hrs.

Cement No. i:

1 r 37. 1 1. 6 2, 736 35. 8 1. 7 3, 323 5:8 2'23? oemn't'iiT'zi l Retardation of set is indicated by e sign and acceleration of set by a sign.

1 On a solids basis, based on the weight oi cement.

The results set forth in Table No. II clearly show that the efifects of inositol and conventional accelerators are additive so that a desired combination of benefits can be achieved by the use of inositol with one or more set accelerating agents. Thus, both the water requirements and the 7- and 28-day compressive strengths of mixes 2-4 of Cement No. 1 are improved over the results for mix No. 1 when inositol is incorporated into the mix together with triethanolamine. Significantly, these desired benefits are obtained without any retarding effect on the setting time of the concrete. The data for cement mixes 5 and 6 of Table No. II demonstrate the effetcivess of a three-component admixture comprising inositol, triethanolamine and calcium chloride with respect to the water requirements of the mix, 7- and 28day compressive strength and the setting time of the concrete.

It is also within the scope of the invention to employ inositol together with known set retarders, such as lignosulfonates, sugars, glucosaccharides, and the like, or combinations thereof to obtain improvement in the compressive strength of the hardened mix, but with less retarding eifect than would result from such set retarders. Inositol and said known set retarders can also be employed together with conventional set accelerators as mentioned above to achieve a desired combination of benefits. For example, inositol has been employed together with glucosaccharides to achieve improved compressive strength, the presence of inositol reducing the amount of TEA and CaCl employed below that required in the absence of the inositol to produce a rate of hardening equal to that of the concrete mix of lower compressive strength in the absence of such admixtures. Similar results can be obtained when other set retarders, such as lignosulfonates, are used together with inositol and known accelerators.

Inositol, therefore, is an additive for hydraulic cement mixes that offers significant advantages in the art, permitting highly desirable benefits to the art. While the invention has been described herein with reference to particular embodiments thereof, it will be appreciated that various changes and modifications can be made therein without departing from the scope of the invention as set forth in the appended claims.

Therefore, we claim:

1. A hydraulic cement mix comprising cement, aggregate, sufficient water to effect hydraulic setting of the cement, and an additive comprising inositol, said additive being present in an amount above about .005 by weight of cement sufficient to increase the compressive strength of the hardened concrete formed upon setting of said mix, whereby a reduction of the water content of the mix for a given plasticity and an increase in the compressive strength of the hardened concrete is achieved while minimizing the retarding of the rate of set and the development of early strength that normally accompany such an improvement in the compressive strength of hardened concrete.

2. The mix of claim 1 in which said inositol is present in an amount within the range of from about 0.005% to about 0.75% by weight of cement.

3. The mix of claim 2 in which said inositol is present in an amount within the range of from about 0.025% to about 0.25% by weight of cement.

4. The mix of claim 3 in which said inositol is present in an amount within the range of from about 0.025 to about 0.10% by weight of cement.

5. The mix of claim 4 in which said range is from about 0.05 to about 0.10% by weight.

6. The mix of claim 1 in which said range is from about 0.50% to about 0.75% by weight of cement, whereby the increase in strength of the hardened mix is enhanced in applications in which excessive retardation of set can be tolerated.

7. The hydraulic mix of claim 1 and including therein an admixture comprising a set accelerating agent in an amount sufficient to accelerate the rate of hardening of the cement, the effect of said inositol and said accelerating agent being additive so as to increase the rate of hardening of the mix while at the same time enhancing the compressive strength of the hardened mix.

8. The mix of claim 7 in which said accelerating agent is taken from the group consisting of triethanolamine, calcium chloride and combinations thereof.

9. The mix of claim 8 in which said accelerating agent comprises calcium chloride.

10. The mix of claim 8 in which said accelerating agent comprises triethanolamine.

11. The mix of claim 8 in which said inositol is employed in an amount within the range of from about 0.005 to about 0.75% by weight of cement.

12. The mix of claim 8 in which said inositol is employed in an amount within the range of from about 0.025 to about 0.10% by weight of cement.

13. The mix of claim 8 and including therein a set retarding admixture.

14. A process for improving the properties of hydraulic cement mixes comprising cement, aggregate and sufiicient water to effect hydraulic setting of the cement, said process comprising adding inositol to said mix in an amount above about .005% by weight of cement sufficient to increase the compressive strength of the hardened concrete formed upon setting of the cement mix, whereby a reduction in the water content of the mix for a given plasticity and an increase in the compressive strength of the hardened concrete is achieved while minimizing the retarding of the rate of set and the development of early set of the resulting concrete normally accompanying such improvement in compressive strength.

15. The process of claim 14 in which said inositol is employed in an amount within the range of from about 0.005% to about 0.75% by weight of cement.

16. The process of claim 15 in which said inositol is employed in an amount within the range of from about 0.025% to about 0.25 by weight.

17. The process of claim 16 in which said inositol is employed in an amount within the range of from about 0.025% to about 0.10% by weight of cement.

18. The process of claim 17 in which said range is from about 0.05% to about 0.10% by weight.

19. The process of claim 14 in which said range is from about 0.50% to about 0.75% by weight of cement.

20. The process of claim 14 and including adding an admixture comprising a set accelerating agent in an amount sufficient to accelerate the hardening of the cement, the effect of said inositol and said accelerating agent being additive so as to increase the rate of hardening of the mix while at the same time enhancing the compressive strength of the hardened mix.

21. The process of claim 20 in which said accelerating agent is taken from the group consisting of triethanolamine, calcium chloride and combinations thereof.

22. The process of claim 21 in which said inositol is added in an amount within the range of from about 0.005% to about 0.75% by weight of cement.

23. The process of claim 20 in which said range is from about 0.025 to about 0.10% by weight of cement.

24. A dry hydraulic cement mix comprising cement and an additive comprising inositol, said additive being present in an amount above about .005 by weight of cement suflicient to increase the compressive strength of the hardened concrete formed after sufiicient water is added to the dry cement mix to etfect hydraulic setting of the cement, whereby a reduction of the water content and an increase in the compressive strength of the hardened concrete is achieved while minimizing the retarding of the rate of set and the development of early strength that normally aocompany such an improvement in the compressive strength of the hardened concrete.

25. The mix of claim 24 in which said inositol is present in an amount within the range of from about 0.005 to about 0.75 by weight of cement.

26. The mix of claim 25 in which said inositol is present in an amount within the range of from about 0.025% to about 0.25% by weight of cement.

27. The mix of claim 26 in which said inositol is present in an amount within the range of from about 0.025% to about 0.10% by weight of cement.

28. The mix of claim 27 in which said range is from about 0.05% to about 0.10% by weight.

29. The mix of claim 24 in which said range is from about 0.50% to about 0.75% by weight of cement, whereby the increase in strength of the hardened mix is enhanced in applications in which excessive retardation of set can be tolerated.

30. The hydraulic mix of claim 24 and including therein an admixture comprising a set accelerating agent in an amount suificient to accelerate the rate of hardening of the cement, the effect of said inositol and said accelerating agent being additive so as to increase the rate of hardening of the mix while at the same time enhancing the compressive strength of the hardened mix.

31. The mix of claim 30 in which said accelerating agent is taken from the group consisting of triethanolamine, calcium chloride and combinations thereof.

32. The mix of claim 31 in which said accelerating agent comprises calcium chloride.

33. The mix of claim 31 in which said accelerating agent comprises triethanolamine.

34. The mix of claim 31 in which said inositol is employed in an amount within the range of from about 0.005% to about 0.75% by weight of cement.

35. The mix of claim 31 in which said inositol is employed in an amount within the range of from about 0.025 to about 0.10% by weight of cement.

36. The mix of claim 31 and including therein a set retarding admixture.

References Cited UNITED STATES PATENTS 3,432,317 3/1969 Kelly et al. 106-92 3,090,692 5/1963 Kelly et a1. 10692 2,311,288 2/1943 Booth 10692 JAMES E. POER, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE 744 CERTIFICATE (FF (IQRRECTION Patent No. 9 725,097 Dated Apr. 3, 1973 Inventor(s) Richard B. Peppler et 9.1

It is certi fied that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 2, line 6, change "one" to on line 9, change "these" to there line 23, change "compresive" to compressive line 63, change "C H (OH) -2H O" to C H (OH) -2H O i In Column 3, TABLE I, the 6th heading in the Table, change "Compressive Compressive strength of to strength of concrete, p.s.i. in-" concrete, psi

same table, the 6th column, the first listing under "7 days" change "2. 870" to In Column 4, TABLE II, the 7th heading in the Table, change Compressive Compressive strength of strength of concrete, concrete, psi p.s.i. in-" to Signed and sealed this 18th day of September 1973.

(SEAL) Attesc:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEJT TER Attesting Officer Acting Commissioner of Patents FORM po'wso (1M9) USCOMM-DC 6O376-P69 U-S. GOVERNMENT PRINTING OFFICE; III '-Il."$ll,

NiTEn STATES PATENT OFFICE CERTIFICATE or coRREeTioN 9 Patent No. 3,725,097 Dated Apr. 3, 1973 Inventor(g) Richard B. Peppler et 9.1

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 2, line 6, change "one" to on line 9, change "these" to there line 23, change "compresive" to compressive line 63, change "C H (OH) .2H O to C H (OH) -2H O In Column 3, TABLE 1, the 6th heading in the Table, change "Compressive Compressive strength of to strength of concrete, p.s.i. in-" concrete, psi

same table, the 6th column, the first listing under "7 days" change "2.870" to In Column 4, TABLE II, the 7th heading in the Table, change Compressive Compressive strength of strength of concrete, concrete, psi p.s.i. in" t0 Signed and sealed this 18th day of September 1973.

(SEAL) Attest:

EDWARD M.FLETCPER,JB. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents FORM PC4050 (19.69) USCOMM-DC 0O376-P69 i U. 5. GOVERNMENT PRINTING OFFICE: I'll O36l-33l,

CERTIFICATE OF CORRECTION Patent NO. Dated P Inventm-( Richard B. Peppler et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 2, line 6, change "one" to on line 9, change "these" to there line 23, change "compresive" to compressive line 63, change "C H (OH) -2H O" to C H (OH) -2H O In Column 3, TABLE I, the 6th heading in the Table, change "Compressive Compressive strength of to strength of concrete, p.s.i. in" concrete, psi

same table, the 6th column, the first listing under "7 days" change "2. 870 to In Column 4, TABLE II, the 7th heading in the Table, change Compressive Compressive strength of strength of concrete, concrete, psi p.s.i. in-" 7 110 Signed and sealed this 18th day of September 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTFrsYnH Attes'ting Officer Acting Commissioner of Patents FORM PO- 0 0 (10-69) USCOMM-DC 60376-P69 U.S, GOVEINMEN! PRINTING OFIICE: "I! O-JGl-SJI. 

